Polymorphic Associations and REST

Has anyone gotten this to work in Rails?

What exactly you mean?

REST works fine with poly..
Like this:
  map.resources :communities do |communities|
    communities.resources :comments do |comments|
      comments.resources
    end
    communities.resources :feeds
  end

Then you can use link_to "New Comment",
new_comment_url(@community) restfully (with propriate actions!)